Oak Ridge National Environmental Research Park

Research Park Notes
Issue 7, February 20, 2001

Welcome to Research Park Notes! Look for tidbits of information on National Environmental Research Park activities, observations, and users every couple of weeks. To provide newsletter input, request additional information, make comments, or add/delete mailing list names, contact the Oak Ridge National Laboratory Area Manager, Pat Parr.

PARK RESEARCH AND USERS

Long term measurements of ecosystem properties are critical for understanding the ecological effects of changes in climate and atmospheric chemical deposition resulting from human activities. Researchers in Oak Ridge National Laboratory’s Environmental Sciences Division and visiting scientists have maintained records of key hydrological, chemical, and biological measurements in Walker Branch Watershed in the Oak Ridge National Environmental Research Park over the past three decades. Walker Branch is used also as an outdoor laboratory for tracer experiments to study controls on nutrient cycling in forests and streams. Concerns about the effects of atmospheric deposition of sulfur and nitrogen have led researchers to study the role of the forested watershed ecosystem in the uptake and retention of these pollutants. Analysis of the long term records of deposition and stream water outputs from Walker Branch shows that the ecosystem retains only about onethirdd of the deposited sulfur. In contrast, the Walker Branch records show that nitrogen deposition is increasing, but the watershed ecosystem retains almost all of the deposited nitrogen, and stream water outputs have remained very low. A major question is whether this highly efficient retention of nitrogen will continue indefinitely, particularly if the climate changes.

As interest is increasingly focused on effects of rising atmospheric carbon dioxide (CO2) and the rate at which carbon is removed from the atmosphere and stored in ecosystems, better methods are needed to study below-ground carbon dynamics. Park researchers have recently developed and tested a technique for determining catchmentscale rates of below-ground CO2 flux. This technique uses long term records of stream water chemistry data with a geochemical weathering model and direct measurements of instream processes involving CO2 (metabolism, airwater exchange) to calculate soil gas CO2 concentrations and evasion rates. Catchmentscale soil CO2 evasion rates calculated using the long term Walker Branch stream chemistry records show the expected seasonal variations and agree relatively well with short term measurements using forest floor chambers.

To better understand the role of stream ecosystems in nitrogen uptake and retention in forested landscapes, Park researchers have conducted Nitrogen-15 tracer addition experiments in the West Fork of Walker Branch. Results of these experiments show that ammonium uptake rates are very high and that outputs of nitrogen are strongly influenced by nitrification rates and uptake of nitrate within the stream. The most important controls on nitrate uptake were the demands for nitrogen by algae, bryophytes, and microbes associated with decomposing organic matter and the availability of ammonium to meet those demands. This research has demonstrated that the uptake and cycling of nitrogen within the stream is an important consideration in interpreting stream water outputs from the watershed.

For more information on Walker Branch Watershed research, see the Web site at http://www.esd.ornl.gov/research/mulholland_highlight.html. This research is sponsored by the Department of Energy’s Office of Biological and Environmental Research, the National Science Foundation, and the National Oceanic and Atmospheric Administration.

NATURAL RESOURCES AND MANAGEMENT

Rare Plants - Larry Pounds, Botanical Consultant

We are continually reminded that our knowledge of the reservation’s natural resources is incomplete. Here are a couple of interesting observations that Larry Pounds thought might be of interest to our readers. During 2000, four new occurrences of state-listed plant species (goldenseal, tubercled rein-orchid, Canada lily, and Spreading false-foxglove) were found on the Oak Ridge Reservation. This information has been sent to The Heritage Division of the Tennessee Department of Conservation in Nashville for their records. The information will also be added to The Nature Conservancy’s Biological Conservation Database (which includes Oak Ridge Reservation rare species data). These four species are part of the 21 state-listed rare plant species known to occur on the reservation. See the Research Park Web site for a complete listing of reservation rare plants at http://www.esd.ornl.gov/facilities/nerp/data.html.

Larry also notes that the Canada lily (threatened in Tennessee) occurrence was in an area on the reservation where we had thought the lily had been extirpated. Flowering was observed this year at this site making this the only reservation site where flowering was seen in 2000 for this species. At the only site known to have produced flowers in 1999, there was no flowering this year.

COMMUNITY NOTES

A Tennessee chapter of The American Chestnut Foundation is being formed. Joe Wolfe, an ORNL employee, is acting as secretary and Web master for the core group who is starting the chapter. Anyone interested in the Tennessee chapter of The American Chestnut Foundation can contact Dan Hurst (hurstdp@aol.com) or check out the Web site (which also includes meeting dates and location) at http://www.serversolutions.com/wolfe/chestnut/default.htm.

April 25-29, 2001  The 16th Annual Symposium of the U.S. Regional Chapter of the International Association of Landscape Ecology (US-IALE), Arizona State University, Tempe, Arizona. More info: http://www.west.asu.edu/LEML/iale2001.

May 29-June 2, 2001  American Geophysical Union (AGU) meeting in Boston. Abstracts are due March 8. In addition to its strength in subsurface science and geochemistry, AGU is continuing to expand its focus on biogeoscience and watershed hydrology. Check the Web site for more details: http://www.agu.org/. Also note that Annett Sullivan of Oak Ridge National Laboratory’s Environmental Sciences Division is convening a special session on water quality of natural systems.

August 5-10, 2001  The 86th Annual Meeting of the Ecological Society of America, Madison, Wisconsin. More info: http://esa.sdsc.edu/madison/.

October 3-6, 2001  Natural Areas Association Annual Conference at Cape Canaveral, Florida, on “Searching for a Natural Balance.” For more information, see http://natareas.org/frame.htm.